Micro-pipes can offer solutions for a variety of industries for a variety of applications. It is important to control the size of the micro-pipes as well as the feasibility of the method to produce them suited for their function.
One of the conventional methods of forming micro-pipes is disclosed in U.S. Pat. No. 6,228,744 B1. In this disclosure, a micro-pipe is formed by forming a second layer over a first layer, on a substrate having a trench with a height larger than a width thereof, so that the second layer lines sidewalls and bottom of the trench and covers the top of trench to form the micro-pipe within the trench. A drawback inherent to this disclosed method is that it is unsuitable for producing micro-pipes within a trench having a width less than 100 nm, since the filling characteristics of the trench by the second layer may be limited for the formation of micro-pipes.
Another conventional method of fabricating a micro-pipe is disclosed in US 2005/0215025 A1. In this disclosure, a trench is provided in a base layer on a substrate. A photoresist layer on the base layer covers the trench. Subjecting the photoresist layer to ionizing radiation forms a micro-pipe. A drawback inherent to this disclosed method is that the radius of curvature of the deformed photoresist portions may be dependent on a variety of factors including the photoresist material type, the thickness of the photoresist layer, the width and depth of the patterned openings, the wavelength and intensity of irradiation and the ambient pressure. Furthermore, the disclosed method is suited for producing large micro pipes, where by a photoresist layer having a thickness of about 1 um to about 100 um is provided.
Therefore, there is a need in the art for producing structures comprising single or multiple layers of micro-pipes having a cross section taken perpendicularly to their longitudinal direction having a maximal extent less than 100 nm.